1. Field of the Invention
This invention relates to a lens barrel and an image pickup apparatus.
2. Description of the Related Art
An image pickup apparatus such as a digital still camera or a digital video camera has a lens barrel provided therein.
A lens barrel of the type is known which includes a lens moving frame for holding an image pickup lens thereon and a barrel member for supporting the lens moving frame for back and forth linear movement along the direction of an optical axis of the image pickup lens. The lens moving frame is moved by a zooming action or a focusing action.
In order to control the movement of the lens moving frame, it is necessary to detect the amount of movement of the lens moving frame. To this end, a magnetized face is formed on the lens moving frame such that N poles and S poles are magnetized alternately along the direction along which the lens moving frame is moved back and forth linearly. A magnetic resistance sensor device is provided on the barrel member and detects the magnetized face to generate a detection signal corresponding to the amount of movement of the lens moving frame. A lens barrel of the type just described is disclosed, for example, in Japanese Patent Laid-open No. 2000-2559.
Incidentally, in order to obtain a detection signal of high quality from the magnetic resistance sensor device, it is necessary to precisely adjust the gap between a sensing face of the magnetic resistance sensor device and the magnetized face. In the lens barrel described, the magnetic resistance sensor device is rocked to move the sensing face toward or away from the magnetized face to perform the adjustment of the gap.